a. Field of the Invention
The instant disclosure relates to elongate medical devices. Specifically, the instant disclosure relates to the design and construction of elongate medical devices with independently-deflectable shaft segments and handles for deflecting those shaft segments.
b. Background Art
Catheters are used for an ever-growing number of procedures. For example, catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, the catheter is manipulated through the patient's vasculature and to the intended site, for example, a site within the patient's heart. The catheter typically carries one or more electrodes, which may be used for ablation, diagnosis, or the like.
To increase the ability to move and navigate a catheter within a patient's body, steerable catheters have been designed. Steerable catheters are often manipulated by selectively tensioning one or more pull wires (or deflection wires) running along the length of the catheter, typically offset from a central axis of the catheter, thereby deflecting the distal end of the steerable catheter in one or more planes. These pull wires are often attached to a metallic catheter component located at the distal end of the catheter, such as one of the electrodes carried on the distal end of the catheter or a pull ring incorporated in the catheter.
Steerable catheters often have a steering mechanism near the distal end of the catheter. This steering mechanism typically includes a pull ring and one or more pull wires (or deflection wires) attached thereto and extending proximally towards an actuator that can place the wire or wires in tension. Placing a pull wire in tension causes the distal end of the catheter to deflect in at least one plane. In this fashion, the catheter can be navigated through the tortuous path of a patient's vasculature to a target site. Because of the length of the path that a catheter may need to travel to reach a target site, however, deflectability of only the distal end of the catheter may not provide the practitioner with as great a level of steerability as the practitioner might desire.
In addition, once the catheter has been positioned at the target site, it often becomes necessary for the catheter to assume a particular shape in order to perform its desired function (e.g., a spiral shape for electrophysiological mapping of the ostium of a pulmonary vein). Deflectability of only the distal end of the catheter may not provide the practitioner with the flexibility to deform the catheter into all desirable shapes.
Like known catheter shafts, known control handles for controlling deflection of catheter bodies have several drawbacks that adversely impact the handles' ability to be operated. First, the control handles are often excessively bulky. Second, the control handles are often inadequate with respect to their ability to provide finely controlled deflection adjustment for the distal end of the catheter body. Third, the control handles often provide inadequate deflection wire travel for a desired medical procedure. Fourth, the control handles often have a mechanical advantage that is less than desirable and, as a result, require significant effort to operate on the part of a user. Fifth, once a desired body distal end deflection has been reached, the control handles typically require the physician to take a conscious step to maintain the catheter at the desired deflection. Sixth, the wire displacement mechanisms within the control handles have a tendency to permanently deform the deflection wires. Seventh, the wire displacement mechanisms within the control handles typically make it difficult, if not impossible, to provide a lumen that runs uninterrupted from the proximal end of the control handle to the distal end of the catheter body.
There is therefore a need for a catheter that minimizes or eliminates one or more of the problems set forth above.